I am sure all of us would say “use”. Using a calorie means it goes into the body and is immediately used as fuel. Storing means I will use it later, which means it becomes adipose tissue. You may know adipose tissue by its street name: FAT.
Of course, you cannot will yourself to do one or the other. This is an involuntary response by the body based on insulin levels. Therefore, what you eat, how fast you eat and your sensitivity to insulin will determine if it goes in the metabolic fire or on your parabolic hips.